1. Field of the Invention
The present invention may be directed to safety equipment, and in particular to an arresting device with associated triggering equipment, utilized in an elevator cage running along predefined guides. The elevator cage may be used to convey persons and/or goods. The safety equipment may recognize when the elevator cage exceeds a permissible speed of travel in either an upward or downward direction, and stop the elevator cage. The safety equipment may utilize a trigger lever, connected with a limiter cable, that is effective in both directions of travel.
2. Discussion of the Background Information
Safety equipment, similar in general to the device of the present invention, protects the passengers in an elevator cage against physical injury when a permissible speed is exceeded in the upward direction, i.e., the upward case.
The prior art safety equipment constructed for the above-noted purpose consists of an arresting device, effective in both directions of travel, at the elevator cage and triggering equipment. The triggering equipment consists of a speed limiter responding in both directions of rotation, a limiter cable with a tensioning device and fracture checking equipment, and a trigger lever connected with the limiter cable at the elevator cage.
A double arresting device, having separate or connected brake chocks for each direction of travel, is disclosed in schematic illustration by European Patent Specification No. 0 440 839. The brake chocks are provided on only one side of the guide rail and, during arresting, are supported by a passive abutment plate on the other side of the guide rail. In an arresting device of this type, a transverse displaceability of the arresting device under load must be provided to enable centering of the device during an arresting operation. No solution is disclosed for this problem in the prior art. Upon triggering, the brake chock of the prior art, which does not participate in the arresting and which moves in the opposite direction of travel, is actuated in the opposite sense and is pushed out of its rest position. This result is undesirable, however, given in the prior art it was through that the constructional formation of this equipment for practical use would probably lead to a cost-intensive solution.
A double arresting device, according to U.S. Pat. No. 5,096,020, also operates with a respective chock for each direction of travel, but in an oppositely disposed arrangement. A common trigger lever engages with entraining slots in the arresting chocks. Upon triggering, this arresting device must be laterally displaced until lying against the passive chock of the opposite direction. The transverse displacement under load requires rolling friction for reliable centering, which requires a corresponding additional constructional effort.
Another double arresting device is disclosed in U.S. Pat. No. 5,230,406. In this arresting device, the arresting chocks are disposed at both sides of the guide rail and, as shown in FIGS. 6-9, each are constructed for both directions of travel, i.e., each includes a double ramp in different shapes at a rear side. During downward arresting the brake chocks are drawn into the arresting position by rods. During upward arresting, the brake chocks are pushed by the same rods into the arresting position. However the equipment requires additional equipment for practical construction, for example, specially constructed retaining springs, chock guides and adjusting devices.
The above-mentioned examples of prior art double arresting devices disclose special constructions, which entail new variants for equipment which is known in principle. However, special construction contradicts the endeavor for standardization and for reduction in diversity of parts and makes the rational application of an economical modular construction technique more difficult.